Feasibility of a short acquisition protocol for whole-body positron emission tomography with fluorine-18 fluorodeoxyglucose.

The conventional protocol for whole-body positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) requires a total acquisition time of 40-60 min, which is inconvenient for many oncological patients owing to fatigue and discomfort. This study examined the feasibility of a short protocol for whole-body PET. A phantom containing six "hot" spheres of gradually increasing diameter (10-38 mm) was imaged using a dedicated PET scanner for 20, 40, 60, 80, 120 and 600 s at various count rates. Thirty-four patients with various neoplasms underwent whole-body emission scans for 1 min per bed position 1 h after intravenous injection of 370 MBq of FDG (short protocol). A standard simultaneous transmission-emission acquisition for 10 min per bed position was performed thereafter. The images were reconstructed using an iterative algorithm. At a count rate of 40 kcps, which is close to the average count rate obtained in a whole-body FDG PET study, the 60-s image visualised five spheres, of which the smallest was 13 mm in size. Despite the better image quality, lesion detection was not improved in images acquired for more than 60 s (80-600 s). Only three of the six spheres could be detected in images acquired for less than 60 s. In the patient study, the standard protocol visualised 120 tumour lesions, of which 93 (78%) could be detected using the short protocol. Among the non-visualised lesions, 22 (82%) were < or =1.5 cm in size and 17 (63%) were lymph nodes. It is concluded that the proposed short protocol for whole-body FDG PET has a reasonably high detection rate and may be suitable for patients who are unable to undergo scanning for a prolonged period. It may also be useful as a pre-scan guide before a standard whole-body acquisition.     

Oncological applications of positron emission tomography with fluorine-18 fluorodeoxyglucose

Positron emission tomography (PET) is now primarily used in oncological indication owing to the successful application of fluorine-18 fluorodeoxyglucose (FDG) in an increasing number of clinical indications at different stages of diagnosis, and for staging and follow-up. This review first considers the biological characteristics of FDG and then discusses methodological considerations regarding its use. Clinical indications are considered, and the results achieved in respect of various organs and tumour types are reviewed in depth. The review concludes with a brief consideration of the ways in which clinical PET might be improved.     

Sclerosing mediastinitis: findings on fluorine-18 fluorodeoxyglucose positron emission tomography

Whole-body serial positron emission tomography scanning was done using fluorine-18 fluorodeoxyglucose (F-18 FDG) in a patient with a mediastinal mass. Uptake correlated well with the clinical symptoms and aggressiveness of the disease. Based on the F-18 FDG findings, a biopsy specimen was taken from the active region of the mass, which confirmed the diagnosis of sclerosing mediastinitis.     

Carbon-11 choline positron emission tomography in musculoskeletal tumors: comparison with fluorine-18 fluorodeoxyglucose positron emission tomography

PURPOSE: Recently, a new positron emission tomography (PET) tracer, carbon-11 choline, has been introduced in oncology investigations, but the role of choline PET in musculoskeletal tumor evaluation has not been previously examined. This is the first trial to investigate the utility of choline PET in evaluating musculoskeletal tumors in comparison with fluorine-18 fluoro-2-deoxy-D-glucose (FDG) PET. METHOD: Thirty-three patients were examined with both choline PET and FDG PET, of which standardized uptake values (SUVs) were used for evaluation of the lesions. To decide the appropriate cutoff value and compare the two PET studies, receiver operating characteristic curve analysis was used. The binomial test was used for comparison of sensitivities between choline PET and FDG PET. RESULTS: A significant correlation (r = 0.537, P = 0.0013) between choline and FDG SUVs was noted for all lesions (n = 33). Mean SUVs for malignant tumors were significantly higher than those for benign lesions in both choline PET and FDG PET. Using a cutoff value of 2.7 for choline SUVs, the sensitivity for correctly diagnosing malignancy was 92.3% (12/13) with a specificity of 90.0% (18/20), resulting in an accuracy rate of 90.9%. With use of a cutoff value of 3.3 for SUVs in FDG PET, the sensitivity was 84.6% (11/13) with a specificity of 80.0% (16/20), resulting in an accuracy rate of 81.8%. The receiver operating characteristic curves of two analyses showed that the mean area under the curve value of choline PET (0.9577 +/- 0.041) was significantly greater (P = 0.0488) than that of FDG PET (0.8192 +/- 0.0806). There was no significant difference in sensitivity and specificity between choline PET and FDG PET analysis using either the binomial test (P = 0.4531) or McNemar test (P = 0.371). CONCLUSION: Choline PET analysis may not be inferior to FDG PET analysis for differentiating malignant from benign musculoskeletal tumors. The advantages of choline PET were shorter examination time and little retention in the bladder; therefore, this modality may be useful for preoperative planning for musculoskeletal tumors, especially for lesions around the hip joints.     

Patient preparation for cardiac fluorine-18 fluorodeoxyglucose positron emission tomography imaging of inflammation

Although the number of clinical applications for fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) cardiac positron emission tomography (PET) has continued to grow, there remains a lack of consensus regarding the ideal method of suppressing normal myocardial glucose utilization for image optimization. This review describes various patient preparation protocols that have been used as well as the success rates achieved in different studies. Collectively, the available literature supports using a high-fat, no-carbohydrate diet for at least two meals with a fast of 4-12 hours prior to ¹⁸F-FDG PET imaging and suggests that isolated fasting for less than 12 hours and supplementation with food or drink just prior to imaging should be avoided. Each institution should adopt a protocol and continuously monitor its effectiveness with a goal to achieve adequate myocardial suppression in greater than 80% of patients.     

Optimal scan time for fluorine-18 fluorodeoxyglucose positron emission tomography in breast cancer

Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) has proven useful in the differentiation of various tumour entities, including breast cancer. In patients with primary breast cancer we performed a 3-h imaging protocol to examine possible improvements in tumour detectability and image contrast. Twenty-nine patients with primary breast cancer with a diameter of >/=2 cm that was demonstrated to be malignant by biopsy or surgery were injected with 370-740 MBq 18F-FDG and scanned in the prone position. Data were acquired 0-40 min, 1.5 h and 3.0 h after injection. After correction for measured attenuation, decay and scatter and iterative reconstruction, standardised uptake values (SUVs) and tumour-to-non-tumour and tumour-to-organ ratios were calculated. Visual analysis was performed using transverse, sagittal and coronal slices as well as 3D reprojection images. Tumour-to-non-tumour and tumour-to-organ ratios were significantly higher for the 3-h images than for the 1.5-h images. SUVs did not increase to the same extent. Lesion detectability was 83% in 1.5-h images compared to 93% in 3-h images. We conclude that tumour contrast in breast cancer is improved by starting the PET acquisition at 3 h p.i. rather than at 1.5 h p.i.     

Optimal scan time for fluorine-18 fluorodeoxyglucose positron emission tomography in breast cancer

Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) has proven useful in the differentiation of various tumour entities, including breast cancer. In patients with primary breast cancer we performed a 3-h imaging protocol to examine possible improvements in tumour detectability and image contrast. Twenty-nine patients with primary breast cancer with a diameter of ≥2 cm that was demonstrated to be malignant by biopsy or surgery were injected with 370–740 MBq ¹⁸F-FDG and scanned in the prone position. Data were acquired 0–40 min, 1.5 h and 3.0 h after injection. After correction for measured attenuation, decay and scatter and iterative reconstruction, standardised uptake values (SUVs) and tumour-to-non-tumour and tumour-to-organ ratios were calculated. Visual analysis was performed using transverse, sagittal and coronal slices as well as 3D reprojection images. Tumour-to-non-tumour and tumour-to-organ ratios were significantly higher for the 3-h images than for the 1.5-h images. SUVs did not increase to the same extent. Lesion detectability was 83% in 1.5-h images compared to 93% in 3-h images. We conclude that tumour contrast in breast cancer is improved by starting the PET acquisition at 3 h p.i. rather than at 1.5 h p.i. Received 17 October and in revised form 8 December 1998     

Detection of occult bone metastases of lung cancer with fluorine-18 fluorodeoxyglucose positron emission tomography

Accurate staging of cancer has a critical role in optimal patient management. Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) is superior to CT in the detection of local and distant metastases in patients with non-small cell lung cancer. Although Tc-99 m methylene diphosphonate (MDP) bone scanning is well established in the evaluation of bone metastases, there are conflicting reports on the use of FDG PET in the evaluation of skeletal metastases. We report on a patient with locally advanced lung carcinoma in whom FDG PET accurately identified previously unsuspected widespread asymptomatic bone metastases (bone scan and X-rays negative, confirmed on MRI). Assessment of glucose metabolism with FDG PET might represent a more powerful tool to detect bone metastases in lung cancer compared with conventional bone scans.     

The value of fluorine-18 fluorodeoxyglucose positron emission tomography in patients with medullary thyroid cancer

The early detection of metastases from medullary thyroid cancer (MTC) is important because the only curative therapy consists in surgical removal of all tumour tissue. There is no single sensitive diagnostic imaging modality for the localization of all metastases in patients with MTC. Therefore, in many cases several imaging modalities (e.g. ultrasonography, magnetic resonance imaging, computerized tomography and scintigraphy using pentavalent technetium-99m dimercaptosuccinic acid, thallium-201 chloride, indium-111 pentetreotide, anti-CEA antibodies or metaiodobenzylguanidine) must be performed consecutively in patients with elevated calcitonin levels until the tumour is localized. In this prospective study, we investigated the value of fluorine-18 fluorodeoxyglucose positron emission tomography ([¹⁸F]FDG PET) in the follow-up of patients with MTC. [¹⁸F]FDG PET examinations of the neck and the chest were performed in 20 patients with elevated calcitonin levels or sonographic abnormalities in the neck. Positive [¹⁸F]FDG findings were validated by histology, computerized tomography or selective venous catheterization. [¹⁸F]FDG PET detected tumour in 13/17 patients (nine cases were validated by histology, four by computerized tomography). Five patients showed completely negative PET scans (of these cases, one was true-negative and four false-negative). One patient with [¹⁸F]FDG accumulation in pulmonary lesions from silicosis and one patient with a neck lesion that was not subjected to histological validation had to be excluded. Considering all validated localizations, [¹⁸F]FDG PET detected 12/14 tumour manifestations in the neck, 6/7 mediastinal metastases, 2/2 pulmonary metastases and 2/2 bone metastases. In two patients with elevated calcitonin levels, no diagnostic modality was able to localize a tumour. The sensitivity of [¹⁸F]FDG PET in the follow-up of MTC was 76% (95% confidence interval 53%–94%); this is encouraging. [¹⁸F]FDG PET promises to be a valuable diagnostic method, especially for the detection of lymph node metastases, surgical resection of which can result in complete remission. Received 16 September 1999 and in revised form 19 January 2000     

Limited value of fluorine-18 fluorodeoxyglucose positron emission tomography for the imaging of neuroendocrine tumours

Scintigraphy using [¹¹¹In-DTPA-d-Phe¹]-pentetreotide or pentavalent technetium-99m-dimercaptosuccinic acid [^99mTc(V)-DMSA] has been shown to localize well-differentiated and slowly growing neuroendocrine tumours, whereas increased fluorodeoxyglucose (FDG) uptake is associated with malignancy. The aim of this study was to compare the value of fluorine-18 FDG positron emission tomography (PET) with that of somatostatin receptor scintigraphy (SS-R) and dual-radionuclide scintigraphy [SS-R and ^99mTc(V)-DMSA = DNS] in detecting malignant neuroendocrine tumours. Fifteen patients with metastasizing gastroenteropancreatic tumours (GEP tumours; n = 7), medullary thyroid carcinomas (MTCs; n = 8) and elevated tumour markers [GEP tumours: 5-hydroxyindoleacetic acid, insulin; MTCs: calcitonin, carcinoembryonic antigen (CEA)] were studied. Prior to PET, all patients with GEP tumours underwent SS-R. DNS was performed in all patients with MTC. Patients had been fasting for at least 12 h and normal glucose plasma levels were confirmed. Sixty minutes after intravenous administration of ¹⁸F-FDG (mean: 374 MBq) whole-body PET and regional scans were performed. In addition, the resected tissues were prepared for immunocytochemistry examination (cell cycle-associated Ki-67 antigen). In two patients with less-differentiated GEP tumours associated with high proliferative activity and increased FDG uptake, SS-R failed to detect any lesion. In comparison, in four patients with well-differentiated GEP tumours showing low proliferative acitivity, SS-R localized four primary tumours, 22 lymph node metastases and 18 malignant liver lesions, whereas ¹⁸F-FDG PET demonstrated normal distribution. In one patient with a metastasizing carcinoid (medium proliferative activity) SS-R localized multiple metastases, whereas PET demonstrated low FDG uptake in all known metastases. In patients with recurrent MTC and rapidly increasing CEA levels DNS detected only three lesions in two patients, whereas PET demonstrated one pulmonary, three osseous, 20 mediastinal, ten locoregional, and four liver metastases in seven patients. Twenty-nine malignant lesions were confirmed by follow-up and nine lymph node metastases could be surgically removed. In conclusion, PET imaging of gastroenteropancreatic tumours revealed increased glucose metabolism only in less-differentiated GEP tumours with high proliferative activity and metastasizing MTC associated with rapidly increasing CEA levels. Therefore, additional ¹⁸F-FDG PET should be performed only if SS-R or DNS is negative. Received 8 July and in revised form 19 September 1997     

A simplified intravenous glucose loading protocol for fluorine-18 fluorodeoxyglucose cardiac single-photon emission tomography

The myocardial uptake of fluorine-18 fluorodeoxyglucose (FDG) has emerged as the most sensitive and specific technique for the assessment of myocardial viability. With the development of FDG single-photon emission tomography (SPET) and dual head coincidence imaging, a hindrance to the widespread clinical use of FDG cardiac imaging is the complexity of the preinjection glucose loading necessary for obtaining interpretable myocardial FDG scans. In a population of 209 patients undergoing dual-isotope single acquisition (DISA) FDG/sestamibi (MIBI) SPET, we describe the improvements in both image quality and time efficiency using a new short, simple glucose/insulin/potassium (GIK) infusion protocol prior to FDG injection as compared to a conventional oral glucose loading protocol. DISA FDG/MIBI SPET scans were performed in 111 nondiabetic patients after oral loading with 50 g of glucose (group 1). Ninety-eight consecutive nondiabetic patients were subsequently scanned following preparation with a fixed-concentration GIK infusion administered at a standardized rate (group 2). A three-point grading scale was used to assess image quality. The time to FDG injection following glucose administration was significantly shorter for the group 2 patients (39.9±15.6 min; range 20–105 min) than for the group 1 patients (99.5±30.3 min; range 56–270 min) (P<0.0001), representing a 1-h decrease in patient preparation time. More of the group 1 patients (n=30; 27%) required supplemental intravenous boluses of regular insulin than did the group 2 patients (n=13; 13%) (P<0.02). There were more excellent and good quality graded images using the GIK method (group 2) than the more traditional oral loading protocol (group 1) (P<0.02). Nine of 111 scans (8%) in group 1 were uninterpretable, whereas only one of 98 scans (1%) in group 2 was uninterpretable. Standardized infusion of a fixed concentration of GIK prior to FDG administration and continued during myocardial FDG uptake is an effective yet simple method of obtaining consistently good to excellent quality FDG SPET cardiac scans. It is preferable to conventional oral glucose loading due to decreased patient preparation time and improved image quality. The technique is safe and should improve both the clinical use and the cost-effectiveness of FDG SPET imaging for the identification of injured but viable myocardium. Received 2 February and in revised form 12 June 1997     

Staging of non-small-cell lung cancer by whole-body fluorine-18 deoxyglucose positron emission tomography

Positron emission tomography (PET) using fluorine-18 deoxyglucose (FDG), showing increased FDG uptake and retention in malignant cells, has been proven useful to differentiate malignant from benign tissue. We undertook a prospective study in 61 patients to compare the accuracy of whole-body FDG PET and conventional imaging (CI) methods for the staging of nonsmall-cell lung cancer (NSCLC). CI included chest and abdomen computed tomographic scanning and bone scintigraphy. When CI or PET study suggested metastatic disease, confirmation was obtained by biopsy or clinical or radiological follow-up. As compared to CI, PET correctly changed the N stage in 13 patients (21%) and the M stage in six patients (10%). There were three false-positive and no false-negative distant PET findings. Our preliminary results show that whole-body FDG PET can improve the diagnostic accuracy in the staging of NSCLC.     

Rapid detection of human infections with fluorine-18 fluorodeoxyglucose and positron emission tomography: preliminary results

The purpose of this study was to evaluate the feasibility of 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) and positron emission tomography (PET) for rapid detection of human infections. Eleven patients who were known or suspected to be harboring various infections were studied with FDG-PET. Dynamic scans over the putative infection sites were performed immediately after FDG (370 MBq) injection through 60 min, and static images including multiple projection images were then obtained. FDG uptake was assessed visually into four grades (0, normal; 1, probably normal; 2, probably abnormal; 3, definitely abnormal). For the semiquantitative index of FDG uptake in infections, the standardized uptake value of FDG normalized to the predicted lean body mass (SUV-lean, SUL) was determined from the images obtained at 50–60 min after FDG injection. PET results were compared with final clinical diagnoses. Eleven lesions in eight patients, which were interpreted as grade 2 or 3 by FDG-PET, were all concordant with active infectious foci. The SUL values of infections ranged from 0.97 to 6.69. In two patients, FDG-PET correctly showed no active infection. In one patient, it was difficult to detect infectious foci by FDG-PET due to substantial normal background uptake of FDG. In total, FDG-PET correctly diagnosed the presence or absence of active infection in 10 of 11 patients. Fusion images of PET with computed tomography showed the most intense FDG uptake to be within an abscess wall. In conclusion, FDG-PET appears to be a promising modality for rapid imaging of active human infections. More extensive clinical evaluation is warranted to determine the accuracy of this method. Received 5 March and in revised form 20 May 1998